CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
CONSOLIDATED BALANCE SHEETS
Agency MBS, at fair value, pledged as collateral (in dollars)	$ 6,666,963	$ 5,519,879
Non-Agency MBS, at fair value, pledged as collateral (in dollars)	692,534	867,655
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000	5,000
Preferred stock, shares issued	3,840	3,840
Preferred stock, shares outstanding	3,840	3,840
Preferred stock, aggregate liquidation preference (in dollars)	$ 96,000	$ 96,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	895,000	370,000
Common stock, shares issued	356,112	280,481
Common stock, shares outstanding	356,112	280,481